Table 4.
Comparison of the neurocognitive function during the daytime work and after the night shift work of firefighters according to the Patient Health Questionnaire-9 (PHQ-9) category.
| Domain | PHQ-9 Category | N | Mean ± SD (n = 352) | p-Value | |
|---|---|---|---|---|---|
| During Daytime Work | Post Nighttime Work | ||||
| Composite memory | Normal | 298 | 90.1 ± 19.1 | 84.6 ± 19.7 | <0.001 |
| Depression | 54 | 93.3 ± 19.4 | 85.3 ± 19.7 | 0.003 | |
| Verbal memory | Normal | 298 | 87.3 ± 19.8 | 81.1 ± 22.0 | <0.001 |
| Depression | 54 | 90.1 ± 20.9 | 82.7 ± 21.3 | <0.001 | |
| Visual memory | Normal | 298 | 96.8 ± 16.3 | 94.0 ± 16.3 | 0.010 |
| Depression | 54 | 99.1 ± 16.4 | 93.8 ± 18.4 | 0.040 | |
| Complex attention | Normal | 298 | 97.2 ± 19.0 | 93.1 ± 34.0 | 0.030 |
| Depression | 54 | 101.0 ± 12.7 | 94.5 ± 22.1 | 0.017 | |
| Psychomotor speed | Normal | 298 | 112.3 ± 15.8 | 111.0 ± 15.0 | 0.035 |
| Depression | 54 | 112.9 ± 13.5 | 105.4 ± 15.9 | <0.001 | |
| Motor speed | Normal | 298 | 110.6 ± 15.5 | 108.6 ± 14.1 | 0.002 |
| Depression | 54 | 113.2 ± 12.7 | 105.8 ± 14.3 | <0.001 | |
| Processing speed | Normal | 298 | 108.1 ± 15.9 | 108.6 ± 16.9 | 0.626 |
| Depression | 54 | 104.5 ± 14.2 | 101.2 ± 16.8 | 0.143 | |
| Reaction time | Normal | 298 | 92.7 ± 15.1 | 92.5 ± 17.3 | 0.808 |
| Depression | 54 | 90.8 ± 14.5 | 93.7 ± 16.4 | 0.142 | |
| Cognitive flexibility | Normal | 298 | 106.0 ± 17.4 | 105.9 ± 19.0 | 0.921 |
| Depression | 54 | 107.6 ± 14.1 | 105.6 ± 19.7 | 0.471 | |
| Executive functioning | Normal | 298 | 106.8 ± 16.9 | 107.4 ± 18.4 | 0.545 |
| Depression | 54 | 108.2 ± 13.7 | 106.6 ± 19.4 | 0.544 | |
| Neurocognitive index | Normal | 298 | 99.7 ± 12.0 | 97.4 ± 13.6 | <0.001 |
| Depression | 54 | 101.1 ± 9.4 | 96.9 ± 12.1 | 0.003 | |
All subgroups were analyzed by paired t-test.